Comparison of ion exchange process configurations for arsenic removal from natural waters

Influence of process configuration on ion exchange of As(V) was studied using numerical simulations. A new explicit competitive ion exchange model was introduced to facilitate fast computation. Model parameters were determined using published data on arsenic removal from contaminated waters by hydrous ferric oxide (HFO) hybrid materials and strong anion exchangers (SBA). Performance of batch and continuous processes was assessed in terms productivity and resin utilization. It was shown that the HFO resin with very high As(V) selectivity is best utilized in batch operation and counter-current simulated moving bed (SMB) configuration does not give any advantage. The SBA resin has low selectivity for As(V) anions and counter-current operation was found to be essential. A steady state SMB system with continuous removal of the concentrated As(V) fraction was proposed. It was also shown that productivity of both systems can be substantially increased using shallow beds and short loading cycles.